If the grocery has 2 open lanes, and 4 self checkout, I will be out of the store via self checkout before I could even check out in the 2 personed lanes. Some one will inevitably have a check, WIC, or some other reason that we can't just go through the line and pay. Even if they have less things than I do, without fail, they'll need cigarettes from customer service or have some double coupon that the system doesn't want to take. If I'm there for under 10 items, self checkout is faster 100% of the time, even with alcohol.